I'm not sure what I did, but all of a sudden I don't have sound anymore. When I try to play my music, I get the following error message:

 

"Windows Media Player cannot play the file because there is a problem with your sound device.

There might not be a sound device installed on your computer, it might be in use by another

program, or it might not be functioning properly."

 

My computer is a Dell Dimension 2400 desktop

Any Ideas?